Unable to access External Drives and Disk Utility after updating to macOS Sonoma.

I'm almost at the point of ........ I run Windows at work and Mac at home and need my working hard drive (and backups) to open on both. The choice is to move from Apple completely. I can't believe Apple are so disingenuous as not to have fixed this already.

I have been reasonably lucky as sometimes it (my Apricorn secure 2TB drive) opens, sometimes not. Sometimes I can see it in Disc Manager, sometimes not. If I do see it, sometimes a 'repair' (up to three hours) will open it, sometimes not. If I run a disc repair on Windows it will open on my Mac, but only once! If I disconnect it (the correct way) it then can't see it if I plug it back in.

Simply not good enough.............

have the same issue since installed Sonoma. Can see the disk in Disk Utility but can't mount it. When trying to unmount, it says it is in use.

If try to run first aid, says "operation failed. Problems were found with the partition map which might prevent booting. Some information was unavailable during internal lookup. : (-69808).

Bought a new HD thinking the old was damaged and have same issue. When rebooting, get a message that says disk can't be read.

I've tried lot of thinks and absolutely nothing works. Can see the disk on NTFS for Mac and on Disk Utility but can't mount it. it's on grey.

I had to use data recovery software EaseUS. Cost about $100 for one month use. That lets you look inside the unmounted drive and then you can copy files to another drive. I think issue is exFAT formatting and I've changed everything to APFS.

Try leaving your drive with the EFAT partition connected to the computer for about 15-30 minutes. without performing any operations. Observe the behavior of the disk. The disk then carries out the mounting process, which in the case of the Sonoma system takes an absurdly long time. I have a 16 TB WD external drive, it takes almost 30 minutes and only after that time it is mounted and visible in the system. During this time, the Disc Utility system program hangs if I run it. In other words, plug in the disk and do nothing, wait.

HenryMartin wrote:

1. The solution with the brand-new lacie rugged, 4 TB external was to;

delete and remove the “useless seagate” tool kit.

2.

With apple utilities , partition the drive in to 2 partitions. It would not allow me to just directly erase and reformat in to APFS.

3 Now I could erase and reformat the new partition into any APFS.

It didn't have a GUID partition table. That is required for APFS. You could have used the View popup menu to "Show all Devices" and erased the Device, not the mounted volumes. That would also allow you to select GUID Partition Map like the Partition tab allowed.

This is a total disaster for me. It's on a par with when Microsoft launched Windows Vista. It was so broken I threw it out promising never to go back. And now Mac has come to this. External disks not mounting, not being able to connect usb memory sticks and many friends not able to log in to their bank accounts.

totally. Spent 2 hours yesterday with Apple support and was useful. I just realized that can mount the disks through disk utility in safe mode but can't in normal one. Apple asked me to reset from factory settings my mac but don't wanna do it because it'll be a nightmare to get everything back.

According to Apple's long-standing policy, users do not need to have IT knowledge to operate their equipment and systems. And with this problem, you need not only IT knowledge, but also luck. Maybe Apple expects us to spend another few thousand dollars on new equipment to connect an external drive?

I have an external Western myBook Duo (4TB + 4TB) in RAID 1 configuration (USB3.+), formatted exFAT because I have cause to use it with both Mac & Windows. It frequently fails to mount on Mac, and Disk Utility can't repair it. I can still mount it on my Windows system, at which point I can use the Windows Explorer>Properties>Tools>Error Checking, where it always indicates a disk error. Windows then repairs the drive, after which the drive will once again mount on the Mac. I had this same issue with a previous Mac OS (one of the later 10's), but eventually it seemed to have been resolved--until I updated to Sonoma.

I am having a nightmare trying to access my WD 4TB & 5TB hard drives that were formatted NTFS as I use them on both Windows and Mac - but now they will not mount on the Mac since upgrading to Sonoma 14.2.1 - I normally use Paragon NTFS - the small thumb drives will mount but the larger drives will not. I checked both drives on Windows PC and they are fine. Disk Utility shows they are fine and I got a tick for both, but they will not mount on the Mac. I wish I never upgraded to this horrible operating system - I only did it last week - biggest mistake I have made in a while. Is there any solution yet?

Booting into Safe & Recovery and creating another profile to create a work around may work for some, but not all. Has anyone found the reason for the disks vanishing and the only way to see they are physically connected to the usb ports is via system profile and terminal IOREG. Showing and proving the drive is connected and communicating with the computer but the computer will not acknowledge them.

I cannot get a drive number to force mount or eject, I have spoken to support and the drive manufacturers who finally have asked me to run additional reports and forward it to them in order that it may be escalated.

The exFAT drive I was using suddenly kicked back into life however the Time Machine (APFS) and HFS disk is; is in the ether. I can see it on a PC but a disk repair there doesn't work, so it's just sitting here attached to the iMac and I am hoping for a 'Hail Mary' on getting it work again but as each day and week passes this is becoming more unlikely.

I upload everything to the cloud as a double backup and if I need to use a PC, I can always download the records I'm looking for rather than disk formatting types.

Using a MacBook pro M1 with Sonoma 14.2.1.

LaCie 2big RAID external drive with two partitions. 

One for Time Machine formatted APFS GUID Partition Map and one for storage formatted Mac OS Extended (Journaled) GUID Partition Map.

First partition still there.

Second partition with all my work (3TB) disappeared. Greyed not mounting in Disk Utility even in Recovery mode. 

I was using RAID 1 to avoid such situations. No problem before Sonoma.

Creating another profile not making any difference.

Disk utility says failed repair (-69845) or if trying to mount that volume disenter error (-119930868)

What are the chances of a Sonoma update sorting this out?

This has become something worse than just a nuisance. It affects my ability to get my work done. Upgraded to Sonoma 14.2.1 today - still not possible to read usb memory sticks. If it continues I'll just have to switch operating system.

I have been trying to revert to Ventura, as described in several posts in this thread. I hope it will let my new Thunderbolt SSD work properly. Fortunately, my older (slower) drives are okay so far.

But when I try to restore the most recent version of Ventura from Time Machine in Recovery Mode, 13.5.2 (922G91) from an 09/27/23 backup, I get the message

"You must use Migration Assistant to transfer data from this backup. Reinstall macOS if necessary and then use Migration Assistant to transfer data from your backup."

I tried to download a new copy of Ventura from the App Store to make a bootable installer disk, but there I am told "This installer cannot be used from the version of macOS you are running."

There is no option that I can see to download anyway. There is a link to an Apple Support page about making a bootable installer disk, but for that don't you need the Apple installer?

Am I missing a step somewhere?

After completely formatting the disk and installing a clean Sanom installation, the 2 Thunderbolt connectors stopped working completely and I cannot connect an external monitor or external drive.

Can you create an installation disk using an application such as Install Disk Creator.app or other applications if you have the knowledge to use a terminal?